Parents of a 4-month-old girl watch her from a web cam installed over her crib in the Neonatal Intensive Care Unit at Ochsner Medical Center in New Orleans. (AP Photo/Gerald Herbert)

Neonatal intensive care unit (NICU) interventions for babies born very small and early have drastically reduced infant deaths in the United States, but in doing so they've contributed to more intellectual disabilities, according to a new study.

Past research has shown such disabilities have been reduced in recent years through vaccines and newborn screening, for example.

But disability rates may also be rising due to procedures that save the lives of children who go on to have limitations in social and practical skills, according to researchers led by Dr. Jeffrey Brosco.

Of course, that doesn't mean doctors should stop performing life-saving procedures in the NICU and elsewhere, Brosco told Reuters Health.

But the findings are part of a larger trend suggesting researchers and policymakers not focus all of their attention on new medical interventions as the best way to prevent disabilities, but start looking toward public health efforts, he added.

"What this study does is to show that medical intervention has been a two-edged sword," he said.

' Infatuated with...medical technology'

For their report, Brosco and his colleagues reviewed studies published between 1950 and 2000 to look at what conditions contribute to intellectual disabilities and how or why the prevalence of those conditions may have changed over time.

They found babies being born at a low birth weight - less than 2,500 grams or 5 pounds, 8 ounces - and surviving is responsible for 10 to 15 percent of all intellectual disabilities. That could have to do with periods of lack of oxygen or blood flow in those newborns, for example.

However, the study team could not pinpoint any single specific medical intervention introduced during those 50 years that caused disabilities to increase, it wrote in JAMA Pediatrics.

Reductions in intellectual disabilities tied to vaccines and screening have been in the 10- to 15-percent range, according to Baker - meaning the negative effects of medical interventions at least partially cancel out the gains when it comes to disability.

"Americans in general, I think, are infatuated with the role of medical technology and almost tend to see it as synonymous with good health. It is really just part of a much bigger picture," he said.

"The lesson is not that specific interventions cannot be effective in reducing an important cause of child morbidity, such as intellectual disabilities," Baker, who wasn't involved in the new research, told Reuters Health.

And the study shouldn't make people "excessively worried" about care in the NICU, which has improved greatly over the past couple of decades, he said.

"Rather, the lesson is that we do go astray if we focus only on specific medical interventions."

Both Brosco and Baker said public health interventions - such as reducing lead in the environment, preventing substance abuse among teen moms and improving nutrition - may be an equal, if not better, way to boost overall health and reduce intellectual disabilities in particular.

"Health is much more than just what doctors do," Brosco said. "Health is related to what individuals do and also to how we construct our environments. We need to pay at least as much attention that."